I started watching boxing because of my grandfather about 20 years ago. The Ali wars with Foreman, Norton and Frazier were on TV all the time and my grandfather was watching them and so I watched with him. It was interesting at first, but only a few years later did I develop an interest myself and started reading boxing magazines (Ring, KO) and I watched european boxing on Eurosport. Later did I start to watch international boxing and develop an interest in ALL divisions because at first I was only interested in the HW division like most "casual" boxing fans.
It is indeed a process to study this sport. I would say I study boxing history since around 14 years now and even today I hear new stories I never heard before.